Metastableh-MoO₃and stableα-MoO₃microstructures: controllable synthesis, growth mechanism and their enhanced photocatalytic activity

Abstract

Metastable h-MoO 3 hexagonal prisms have been fabricated through a simple green ultrasonic-assisted chemical route. After calcination at 440 C for 2 h, the thermodynamically stable a-MoO 3 nanoplate-based rods have been achieved through a process of in situ phase transformation. The as-synthesised products have been characterised by powder X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectrum, UVÀvis diffuse reflection spectroscopy and photoluminescence spectroscopy. The phase transformation from metastable h-MoO 3 to stable a-MoO 3 is observed at 419 C according to the differential scanning calorimetry results. The possible growth mechanism of MoO 3 crystals has been proposed based on the experimental results. The prepared two kinds of MoO 3 samples both display higher photocatalytic performance for degrading rhodamine B compared to that of commercial MoO 3 . In the present system, a-MoO 3 nanoplate-based rods exhibit slightly higher degradation activity than h-MoO 3 hexagonal prisms, which is possibly due to its smaller band gap energy, smaller scale of nanoplate, better adsorption capacity and lower recombination of photogenerated electrons and holes.

CO2‐Assisted Fabrication of Two‐Dimensional Amorphous Molybdenum Oxide Nanosheets for Enhanced Plasmon Resonances

“…05‐0508), indicating the poor crystallinity. Meanwhile, for the ultrasonicated sample, it is noteworthy that the diffraction peaks at 19.4° and 25.7°correspond to (200) plane of h‐MoO 3 and (040) plane of α‐MoO 3 , respectively, suggesting that MoO 3 layers have a certain extent crystal structure . XRD analysis are consistent with HRTEM images of both samples.…”

Fabrication of a Single‐Atom Platinum Catalyst for the Hydrogen Evolution Reaction: A New Protocol by Utilization of HxMoO3−x with Plasmon Resonance

“…The X‐ray diffraction (XRD) patterns and Raman spectra of the powder samples shown in Figure a confirm the obtainment of hexagonal molybdenum oxide with a certain extent of amorphization. Three characteristic vibrational modes of both samples at shifts of 690, 900, and 978 cm −1 are observed in the Raman spectrum (Figure b), all of which are in good agreement with hexagonal h‐MoO 3 . Broad Raman bands of amorphous molybdenum oxide can be found at shifts of approximately 860 and 950 cm −1 .…”

“…It can be observed that the pure H x MoO 3− x sample is mostly formed from nanorods with amorphous edges. Usually, hexagonal molybdenum oxide is a metastable phase, which is favorable for its transformation into 2D molybdenum oxide . Besides, the amorphous structure is known to possess high HER activity, primarily as a result of more active sites .…”

Plasma‐assisted synthesis and deposition of molybdenum oxide nanoparticles on polyethylene terephthalate for photocatalytic degradation of rhodamine B

“…The photodestruction of RhB is not observed in the absence of the catalyst. It should be noted that the rate of dye destruction in the presence of the obtained composite is higher than that observed in Reference [67], where 100% degradation was achieved in 180 min for α-MoO 3 nanostructures. At the same time, the obtained rate of destruction of the dye is comparable with the values obtained in Reference [68], where the powder containing MoO 2 nanoparticles was used.…”